1. Technical Field
The present disclosure relates to a recognition device, and more particularly to a fingerprint recognition device.
2. Related Art
With the development of multimedia technologies, more and more portable electronic devices, such as a mobile phone, a Personal Digital Assistant (PDA), a digital camera, and a personal notebook computer, are becoming essential tools in people's lives. However, the portable electronic devices are very personalized and contain lots of private information. Therefore, once the portable electronic devices are lost or stolen, information such as the contact information, photos and data stored inside the portable electronic devices may be obtained by other people, causing unnecessary problems and losses.
Therefore, this type of products need identity (ID) authentication and license management to ensure privacy and security of a user. A main ID authentication method adopted currently is password protection, in which a user at first needs to input a correct password into the portable electronic device before the portable electronic device enters a control menu. However, the password protection is not very secure because the password can be easily leaked or cracked. It is also very troublesome if the user forgets the password. Therefore, a portable electronic device having ID authentication adopting fingerprint recognition becomes available in the market. As all people have different fingerprints, the security of the ID authentication adopting the fingerprint recognition is improved greatly. Moreover, the ID authentication method adopting the fingerprint recognition is convenient that the user does not need to remember the password.
A conventional fingerprint recognition device has a direct-type light source design, in which a diffusion plate is disposed below a finger plate. A number of light sources and an imaging device are disposed at the bottom of the diffusion plate. The light emitted from the light source is diffused through the diffusion plate and then enters the surface of the finger plate, and the fingerprint image of the finger on the finger plate is reflected by the the finger plate and then received by the imaging device. The fingerprint recognition device having the direct-type light source design requires a thicker buffer space to achieve the light diffusion effect, so the thickness of the fingerprint recognition device has to be increased. Moreover, the fingerprint recognition device having the direct-type light source design also requires more light sources to be disposed in a whole area at the bottom of the diffusion plate. In this way, not only the light source cost is increased, but also a bright point phenomenon may occur easily, thereby affecting the imaging quality.